Playstation isn't staying connected to the internet?

Ok. I'm going to explain this as easy as I can. My girlfriend and I purchased the Metal Gear Limited Edition PS3 bundle. We got it online and everything and it was working perfectly fine. Though probably the first few months of having it, we noticed that the internet doesn't want to stay fully connected all the time. And even when we run the connection test, it says that she has 80%+ of connection and it still just doesn't stay connected long. I think the longest it stays on anymore is maybe 10-15 minutes, probably gets about 10% of the playstation updates before canceling and saying that the connection was lost.

My girlfriends sisters boyfriend said that we have the wrong router? if that isn't possibly, we have cable or something and he said we had something like a DSL router or something, I don't know I didn't exactly understand. Though I don't see why it could work just fine and then all of a sudden just not want to connect anymore, or won't stay connected. Specially when our laptops stay connected fine, as far as I know, and the Wii that we even had in the house worked just fine till her sister took it back.

So could it possibly be a 'wrong' router? For this whole thing? I really didn't know there was special routers for different things, and if we got the wrong one how the hell is it even working? Lol. Or is this maybe a PS3 problem? which is what I'm thinking...suggestions?